Limits...
Lotus tenuis x L. corniculatus interspecific hybridization as a means to breed bloat-safe pastures and gain insight into the genetic control of proanthocyanidin biosynthesis in legumes.

Escaray FJ, Passeri V, Babuin FM, Marco F, Carrasco P, Damiani F, Pieckenstain FL, Paolocci F, Ruiz OA - BMC Plant Biol. (2014)

Bottom Line: We recovered a wild, diploid and PA-rich population of L. corniculatus and crossed with L. tenuis.The former grows in an alkaline-salty area in Spain while the latter is a diploid species, grown extensively in South American pastures, which does not accumulate PAs in the herbage.We show that PA levels correlate with expression levels of the R2R3MYB transcription factor TT2 and, in turn, with those of the key structural genes of the epicatechin and catechin biosynthetic pathways leading to PA biosynthesis.

View Article: PubMed Central - HTML - PubMed

Affiliation: IIB-INTECH/CONICET-UNSAM, Chascomús, Bs, As, Argentina. franescaray@gmail.com.

ABSTRACT

Background: Proanthocyanidins (PAs) are secondary metabolites that strongly affect plant quality traits. The concentration and the structure of these metabolites influence the palatability and nutritional value of forage legumes. Hence, modulating PAs in the leaves of forage legumes is of paramount relevance for forage breeders worldwide. The lack of genetic variation in the leaf PA trait within the most important forage species and the difficulties in engineering this pathway via the ectopic expression of regulatory genes, prompted us to pursue alternative strategies to enhance this trait in forage legumes of agronomic interest. The Lotus genus includes forage species which accumulate PAs in edible organs and can thus be used as potential donor parents in breeding programs.

Results: We recovered a wild, diploid and PA-rich population of L. corniculatus and crossed with L. tenuis. The former grows in an alkaline-salty area in Spain while the latter is a diploid species, grown extensively in South American pastures, which does not accumulate PAs in the herbage. The resulting interspecific hybrids displayed several traits of outstanding agronomic relevance such as rhizome production, PA levels in edible tissues sufficient to prevent ruminal bloating (around 5 mg of PAs/g DW), biomass production similar to the cultivated parent and potential for adaptability to marginal lands. We show that PA levels correlate with expression levels of the R2R3MYB transcription factor TT2 and, in turn, with those of the key structural genes of the epicatechin and catechin biosynthetic pathways leading to PA biosynthesis.

Conclusions: The L. tenuis x L. corniculatus hybrids, reported herein, represent the first example of the introgression of the PA trait in forage legumes to levels known to provide nutritional and health benefits to ruminants. Apart from PAs, the hybrids have additional traits which may prove useful to breed forage legumes with increased persistence and adaptability to marginal conditions. Finally, our study suggests the hybrids and their progeny are an invaluable tool to gain a leap forward in our understanding of the genetic control of PA biosynthesis and tolerance to stresses in legumes.

Show MeSH

Related in: MedlinePlus

Relative expression of PA genes in parental and F1 hybrid plants. (a to i) leaves. (j to r) stems. Expression was determined by real-time RT-PCR analysis using EF-1α as the housekeeping gene. Ct value of L. tenuis leaves was arbitrarily selected as reference. Samples are as in Figure 2. Means with similar letter do not differ significantly (p < 0.05), bars indicate standard deviation of mean values.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3927264&req=5

Figure 4: Relative expression of PA genes in parental and F1 hybrid plants. (a to i) leaves. (j to r) stems. Expression was determined by real-time RT-PCR analysis using EF-1α as the housekeeping gene. Ct value of L. tenuis leaves was arbitrarily selected as reference. Samples are as in Figure 2. Means with similar letter do not differ significantly (p < 0.05), bars indicate standard deviation of mean values.

Mentions: In leaves, of the two early PA biosynthesis genes tested by qRT-PCR, namely PAL and CHS, only the latter one displayed a marked difference between parents. CHS expression was also intermediate in the hybrids (Figure 4). When the late PA biosynthesis genes were assayed, it turned out that all the genes, except LAR2, displayed an expression profile that resembled that of CHS in that their expression levels were the highest in L. corniculatus, the lowest in L. tenuis and intermediate in the hybrids. Among these latter genotypes LH4 displayed the highest expression levels for all the genes tested. Conversely hybrids did not differ from L. tenuis for the steady state levels of LAR2 (Figure 4).


Lotus tenuis x L. corniculatus interspecific hybridization as a means to breed bloat-safe pastures and gain insight into the genetic control of proanthocyanidin biosynthesis in legumes.

Escaray FJ, Passeri V, Babuin FM, Marco F, Carrasco P, Damiani F, Pieckenstain FL, Paolocci F, Ruiz OA - BMC Plant Biol. (2014)

Relative expression of PA genes in parental and F1 hybrid plants. (a to i) leaves. (j to r) stems. Expression was determined by real-time RT-PCR analysis using EF-1α as the housekeeping gene. Ct value of L. tenuis leaves was arbitrarily selected as reference. Samples are as in Figure 2. Means with similar letter do not differ significantly (p < 0.05), bars indicate standard deviation of mean values.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3927264&req=5

Figure 4: Relative expression of PA genes in parental and F1 hybrid plants. (a to i) leaves. (j to r) stems. Expression was determined by real-time RT-PCR analysis using EF-1α as the housekeeping gene. Ct value of L. tenuis leaves was arbitrarily selected as reference. Samples are as in Figure 2. Means with similar letter do not differ significantly (p < 0.05), bars indicate standard deviation of mean values.
Mentions: In leaves, of the two early PA biosynthesis genes tested by qRT-PCR, namely PAL and CHS, only the latter one displayed a marked difference between parents. CHS expression was also intermediate in the hybrids (Figure 4). When the late PA biosynthesis genes were assayed, it turned out that all the genes, except LAR2, displayed an expression profile that resembled that of CHS in that their expression levels were the highest in L. corniculatus, the lowest in L. tenuis and intermediate in the hybrids. Among these latter genotypes LH4 displayed the highest expression levels for all the genes tested. Conversely hybrids did not differ from L. tenuis for the steady state levels of LAR2 (Figure 4).

Bottom Line: We recovered a wild, diploid and PA-rich population of L. corniculatus and crossed with L. tenuis.The former grows in an alkaline-salty area in Spain while the latter is a diploid species, grown extensively in South American pastures, which does not accumulate PAs in the herbage.We show that PA levels correlate with expression levels of the R2R3MYB transcription factor TT2 and, in turn, with those of the key structural genes of the epicatechin and catechin biosynthetic pathways leading to PA biosynthesis.

View Article: PubMed Central - HTML - PubMed

Affiliation: IIB-INTECH/CONICET-UNSAM, Chascomús, Bs, As, Argentina. franescaray@gmail.com.

ABSTRACT

Background: Proanthocyanidins (PAs) are secondary metabolites that strongly affect plant quality traits. The concentration and the structure of these metabolites influence the palatability and nutritional value of forage legumes. Hence, modulating PAs in the leaves of forage legumes is of paramount relevance for forage breeders worldwide. The lack of genetic variation in the leaf PA trait within the most important forage species and the difficulties in engineering this pathway via the ectopic expression of regulatory genes, prompted us to pursue alternative strategies to enhance this trait in forage legumes of agronomic interest. The Lotus genus includes forage species which accumulate PAs in edible organs and can thus be used as potential donor parents in breeding programs.

Results: We recovered a wild, diploid and PA-rich population of L. corniculatus and crossed with L. tenuis. The former grows in an alkaline-salty area in Spain while the latter is a diploid species, grown extensively in South American pastures, which does not accumulate PAs in the herbage. The resulting interspecific hybrids displayed several traits of outstanding agronomic relevance such as rhizome production, PA levels in edible tissues sufficient to prevent ruminal bloating (around 5 mg of PAs/g DW), biomass production similar to the cultivated parent and potential for adaptability to marginal lands. We show that PA levels correlate with expression levels of the R2R3MYB transcription factor TT2 and, in turn, with those of the key structural genes of the epicatechin and catechin biosynthetic pathways leading to PA biosynthesis.

Conclusions: The L. tenuis x L. corniculatus hybrids, reported herein, represent the first example of the introgression of the PA trait in forage legumes to levels known to provide nutritional and health benefits to ruminants. Apart from PAs, the hybrids have additional traits which may prove useful to breed forage legumes with increased persistence and adaptability to marginal conditions. Finally, our study suggests the hybrids and their progeny are an invaluable tool to gain a leap forward in our understanding of the genetic control of PA biosynthesis and tolerance to stresses in legumes.

Show MeSH
Related in: MedlinePlus