Awn In Rice

To further investigate the selection of gad1 during rice domestication we used 159 accessions of cultivated rice from 15 countries to compare the appearance of gad1 with two recently identified genes involved in awn development an 1 encoding a basic helix loop helix transcription factor luo et al 2013 and laba1 an 2 encoding a.

Awn in rice.

It was also reported that the genes controlling awn length in rice were always associated with pleiotropic effects on other agronomic traits. In domesticated rice elongation of the awn is partially or completely suppressed in most strains of o. Indica produce an awn. B cultivated rice has either no awns or short and barbless awns and suffers from significant bird predation.

Awn development in rice is also influenced by environment. A long awn is one of the distinct morphological features of wild rice species. The awns of wild rice o. In rice most wild species which belong to the genus oryza generate a long awn on the lemma oka 1988.

A panicle of wild rice tk212 is illustrated in the lower right corner. In grasses awns typically extend from the lemmas of the florets this often makes the hairy appearance of the grass synfloresce. Width ratio rice grains are divided into three size classes namely long medium and short grain for which the ratios range from greater than 3 0 2 1 2 9 and less than 2 respectively bai et al. Grain size is an important factor determining yield in rice.

No awns in panicles were observed under short day conditions but under long day conditions long awns protruded from the apices of lemmas 32. Here we identified a recessive mutant gene grain length and awn 1 gla1 which caused a significant increase in grain length and weight and was associated with long awns the gla1 mutation was mapped to a single nucleotide polymorphism in a gene encoding a cytoplasmically localized mitogen activated protein kinase mapk. Most cultivated varieties of oryza sativa and oryza glaberrima however have lost the ability to form long awns. The causal genetic factors responsible for the loss of awn in these two rice species remain largely unknown.

For example an 1 and an 2 not only regulated awn development but also grain size grain number and other grain characteristics 15 16. Japonica whereas many strains of o. Grass species often harbor long awns. Bar 10 cm.

In botany an awn is either a hair or bristle like appendage on a larger structure or in the case of the asteraceae a stiff needle like element of the pappus. Awns are characteristic of various plant families including geraniaceae and many grasses. 2010 improvements in grain size are directly associated with yield therefore grain size and. Awn domestication asian rice african rice cssls the awn a typical feature of poaceae is a needle like organ extending from the tip of the lemma and is considered to be a modified leaf blade dahlgren et al.

Sativa a wild rice typically bears a long barbed awn which aids in seed dispersal and deters large predators such as birds. Late japonica rice lines nk58 nk58s and nk58sr reportedly showed responses to day length.