Megasporocyte callose in apomictic buffelgrass, Kentucky bluegrass, Pennisetum squamulatum Fresen, Tripsacum L, and weeping lovegrass
Megasporocyte callose in apomictic buffelgrass, Kentucky bluegrass, Pennisetum squamulatum Fresen, Tripsacum L, and weeping lovegrass
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DOI：
10.2135/cropsci1997.0011183x003700030006x
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发表时间：
1997-05-01
期刊：
影响因子：
2.3
通讯作者：
Leblanc, O
中科院分区：
文献类型：
--
作者：
Peel, MD;Carman, JG;Leblanc, O
胼胝质是一种β-1，3-葡聚糖，在被子植物的大孢子母细胞（MMCs）壁中合成和沉积，产生正常的单孢子（>90%的被子植物物种）或双孢子胚囊。这种沉积物在产生四孢子胚囊的被子植物中不存在，最近发现在倍体孢子的披碱草中也不存在。A.作者：Love &康纳spp.，和早熟禾Poa nemoralis L.我们确定了胼胝质沉积的程度，在MMC的倍体的垂穗相思草（画眉草curvula Schrad。），几个另外的倍体孢子的Tripsacum种质和无孢子的水牛草（Pennisetum ciliare（L.）Link）、肯塔基州早熟禾（Peapratensis L.）、和狼尾草（Pennisetum squamulatum Fresen）。用苯胺蓝水溶液清洗雌蕊，用紫外显微镜观察雌蕊中胼胝质的沉积。用干涉显微镜研究了用常规清洗介质清洗的雌蕊。将一些雌蕊在一种澄清培养基中澄清和分析，并在另一种培养基中再澄清和再分析。一个胼胝质MMC中观察到的376个适当阶段的雌蕊从diplosporous物种。这雌蕊，其中89个哭泣Lovegrass雌蕊研究，可能是官能性的。大孢子发生过程中胼胝质的缺失可能是多数倍数孢子体形成类型的特征。虽然存在，胼胝质的分布和数量观察无孢子无融合生殖体MMC壁不规则地减少，可能是由于早期MMC流产或早期激活珠心初始。胼胝质缺乏和空泡化模式支持以下假设：（i）无孢子生殖是由珠心细胞的中度早熟配子体化引起的，和（ii）双孢性、四孢性和倍数孢子生殖是由MMC的中度至极度早熟配子体化引起的，后者几乎完全，而前两种情况下则不完全。了解这些早熟配子体化是如何演变和调节的，可能是至关重要的无融合生殖的主要作物物种的最终转移，并成功地操纵育种。
Callose, a beta-1,3-glucan, is synthesized and deposited in the walls of megaspore mother cells (MMCs) of angiosperms that produce either normal monosporic (>90% of all angiosperm species) or bisporic embryo sacs. Such deposits are absent in angiosperms that produce tetrasporic embryo sacs and were recently shown to be absent in diplosporous Elymus rectisetus (Nees in Lehm.) A. Love & Connor, Tripsacum L. spp., and Poa nemoralis L. We determined the extent of callose deposits in MMCs of diplosporous weeping lovegrass (Eragrostis curvula Schrad.), several additional diplosporous Tripsacum accessions and aposporous buffelgrass (Pennisetum ciliare (L.) Link), Kentucky bluegrass (Pea pratensis L.), and Pennisetum squamulatum Fresen. Callose deposition was studied in pistils cleared in an aqueous aniline blue clearing medium and observed by means of UV microscopy. Pistils cleared with conventional clearing media were studied by means of interference contrast microscopy. Some pistils were cleared and analysed in one clearing medium and recleared and reanalyzed in the other. A callosic MMC was observed in only one of 376 appropriately staged pistils taken from diplosporous species. This pistil, one of 89 weeping Lovegrass pistils studied, was probably facultatively sexual. An absence of callose during megasporogenesis may be characteristic of most types of diplospory. Though present, the distributions and quantities of callose observed in MMC walls of aposporous apomicts were erratically reduced, possibly as a result of early MMC abortion or early activation of nucellar initials. Callose deficiencies and vacuolization patterns support the following hypotheses: (i) apospory is caused by a moderately precocious gametophytization of nucellar cells, and (ii) bispory, tetraspory, and diplospory are caused by a moderately to extremely precocious gametophytization of the MMC that is nearly complete in the latter case and variably incomplete in the former two cases. Understanding how these precocious gametophytizations evolved and are regulated may be crucial to the eventual transfer of apomixis to major crop species and to its successful manipulation by breeders.