Lee Julia M, Sathish Puthigae, Donaghy Daniel J, Roche John R
DairyNZ Ltd, Private Bag 3221, Hamilton 3240, New Zealand.
Pastoral Genomics, ViaLactia Biosciences (NZ) Ltd, PO Box 109185, Newmarket, Auckland 1149, New Zealand.
Funct Plant Biol. 2011 Oct;38(10):808-817. doi: 10.1071/FP11048.
Defoliation severity affects grass regrowth. The changes to biological processes affecting regrowth induced by severe defoliation are not fully understood, nor have they been investigated at a molecular level in field-grown plants. Field-grown perennial ryegrass (Lolium perenne L.) plants were defoliated to 20, 40 or 60mm during winter. Throughout regrowth, transcript profiles of 17 genes involved in photosynthesis and carbon metabolism or transport were characterised in stubble and lamina tissue. Although defoliation to 20mm reduced residual lamina area and stubble water-soluble carbohydrate reserves compared with plants defoliated to 40 or 60mm, net herbage regrowth was not reduced. Transcript profiles indicated a potential compensatory mechanism that may have facilitated regrowth. At the one-leaf regrowth stage, plants defoliated to 20mm had greater abundance of photosynthesis-related gene transcripts (rca, rbcS1, rbcS2, fba, fbp and fnr) and 20% greater stubble total nitrogen than plants defoliated to 60mm. A greater capacity for photosynthesis in outer leaf sheaths may be one potential mechanism used by severely defoliated plants to compensate for the reduced residual lamina area; however, this premise requires further investigation.
落叶严重程度会影响牧草的再生。严重落叶对影响再生的生物过程所造成的变化尚未完全明晰，在田间种植的植物中也未在分子水平上进行过研究。在冬季，将田间种植的多年生黑麦草（Lolium perenne L.）植株刈割至20毫米、40毫米或60毫米。在整个再生过程中，对残茬和叶片组织中参与光合作用、碳代谢或运输的17个基因的转录谱进行了表征。与刈割至40毫米或60毫米的植株相比，刈割至20毫米虽然减少了残留叶片面积和残茬水溶性碳水化合物储备，但牧草净再生量并未降低。转录谱表明存在一种可能促进再生的潜在补偿机制。在一叶期再生阶段，刈割至20毫米的植株与刈割至60毫米的植株相比，与光合作用相关的基因转录本（rca、rbcS1、rbcS2、fba、fbp和fnr）丰度更高，残茬总氮含量高20%。外层叶鞘中更强的光合作用能力可能是严重刈割植株用来补偿残留叶片面积减少的一种潜在机制；然而，这一前提需要进一步研究。
