Plant Height vs. Mesocotyl and Celeoptile Elongation in Rice: Linkage or Pleitropism?

Abstract

Semidwarf cultivars of rice (Oryza sativa L.) produce shorter mesocotyls and coleoptiles than normal‐height rice. Short mesocotyl and coleoptilelongation can cause poor emergence and inadequate stand establishment. The hypothesis has been that, in rice, plant height and mesocotyl and coleoptile elongation are pleiotropic (i.e., one gene controls more than one plant characteristic). Laboratory, greenhouse, and field experiments were conducted to evaluate the relationship of mesocotyl and coleoptile elongation to stand establishment, seedling vigor, and plant height in rice. The potential length of the mesocotyl and coleoptile of semidwarf and standard cultivars was evaluated in the laboratory. The germplasm lines exhibited inherent differences in mesocotyl and coleoptile elongation. The semidwarf germplasm (‘MI01’ and RU7703008) described this study ranged from 75 to 90 cm in height and showed reduced mesocotyl, coleoptile, and total lengths (mesocotyl + coleoptile), whereas the tall plant types (‘L201’ and ‘Labelle’) had comparatively longer mesocotyl, coleoptile, and total lengths. Significant differences were detected among seeding depths and cultivars in the greenhousexperiment for emergence percentage. The field experiment, which was conducted on a Crowley silt‐loam soil (fine, montmorillonitic, thermic Typic Albaqualt), verified that poor stand establishment at deep planting depths of the semidwarf cultivars was associated with short mesocotyls and coleoptiles. Semidwarf germplasm was developed that can produce a long mesocotyi and coleoptile, which demonstrates that plant height and mesocotyi and coleoptile elongation in rice is not due to pleiotropism but to linkage.

Ethylene-Inhibited Jasmonic Acid Biosynthesis Promotes Mesocotyl/Coleoptile Elongation of Etiolated Rice Seedlings

“…Long mesocotyls and coleoptiles may facilitate the emergence of rice seedlings from the soil (Dilday et al, 1990). We then measured the emergence rate of the gy1 mutant and Nip.…”

“…Below the coleoptile, a short stem, also called the mesocotyl, develops in the dark, which pushes the base of the coleoptile toward the soil surface. The elongation of the mesocotyl and coleoptile is regulated by various genetic and environmental factors, which stimulate the emergence of rice seedlings (Takahashi, 1978;Helms et al, 1989;Dilday et al, 1990).…”

A simple, rapid and reliable bioassay for evaluating seedling vigor under submergence in indica and japonica rice (Oryza sativa L.)

“…Deepwater or Xoating rice in fact exhibits extreme elongation capacity under submergence (Kende et al 1998), and hence it can escape complete submergence or full inundation by rapid growth under water. Seedling vigor, which likely plays a key role in avoiding or escaping Xooding stress, is also an important factor in the drill-seeded planting system in rice (Dilday et al 1990). When shoot emergence delays due to low seedling vigor, the rate of seedling mortality increases (Peterson et al 1978).…”

Genetic association of yield with its component traits in a recombinant inbred line population of cotton

“…The existence of correlations between a complex trait and its components is an indication of gene association or pleiotropism (Kebede et al, 2001;Dilday et al, 1990). Correlation analysis, multiple linear regression analysis, and path coefficient analysis are three common methods used to evaluate the relationships between a complex trait and its component traits (Bora et al, 1998;Ball et al, 2001;Cramer & Wehner, 2000;Samonte et al, 1998).…”