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Effect of co-expression of Lc and C1 flavanoid regulatory genes in alfalfa on nutritive value and ruminal methane production
An alfalfa progeny was developed by transforming Lc and C1 genes which are regulatory genes associated with flavonoid pathway in Zea maize. The transformation objective was to promote anthocyanidin accumulation in alfalfa leaves and stems, thus reducing the extent and rate of protein degradation in the rumen and potentially rumen methane production. The objective of this study was to evaluate the effect of co-expression of Lc and C1 genes on (1) protein, energy and feed milk values and (2) methane gas production relative to single gene transformed alfalfa and non-transgenic parent plants. Alfalfa samples were collected at late-bud stage from populations of single gene transformed (C1, Lc1 and Lc3), double gene transformed (Lc1C1 and Lc3C1), parental non-transgenic (NT) and a commercial cultivar (AC-Grazeland: ACGL) maintained in growth chambers at the Saskatoon Research Centre, Agriculture and Agri-food Canada. Samples were chemically analyzed according to AOAC methods and energy and protein values were determined using NRC (2001) and CNCPS (ver.6.1) models. Fermentation gases were obtained from in vitro batch culture and analyzed by gas chromatography for methane. Rumen degradable protein was higher (P<0.01) by 2% in double gene alfalfa comparing to single gene alfalfa, but no differences (P>0.05) were observed in digestible rumen undegradable protein. In comparison to single gene alfalfa, co-expression of Lc and C1 genes increased (P=0.01) net energy by 50 kcal for both lactation and growth and thereby increasing (p<0.01) the feed to milk conversion efficiency by 80 g of milk per kg of alfalfa dry matter. The double gene alfalfa tended to have lower (P=0.07) total gas production than NT alfalfa and significantly lower (P<0.05) methane production by 3.5 L per kg DM than single gene alfalfa. In conclusion, C1 gene when co-expressed with Lc gene improved the feeding value of alfalfa and reduced in vitro methane production.
Keywords: Lc-C1 transgenic Alfalfa, Energy and Protein, Methane