Hybridization and Factors Influencing Seed Set in Oat

Background: Oat is mostly neglected crop for hybrid development due to its floral structure which results in high damage rate during hybridisation. Due to the cumbersome in acquiring a sufficient number of hybrids and subsequent backcrosses are difficult that lead to lack of much inheritance studies in Oats. Methods: The procedure for crossing used was almost identical to that used by oat breeders which was conducted for 2 years viz., 2019-20 and 2020-21 at Forage Station, Punjab Agriculrural University, Ludhiana. Result: The experiment was conducted to know the seed set percent in oat cultivars. Since the oat flower is fragile compared other cereals and it is easily harmed during the emasculation and pollination process. The seed set percent observed was only 12 and 10 percent in the year 2019-20 and 2020-21, respectively.

The Streptochaeta Genome and the Evolution of the Grasses

In this work, we sequenced and annotated the genome of Streptochaeta angustifolia, one of two genera in the grass subfamily Anomochlooideae, a lineage sister to all other grasses. The final assembly size is over 99% of the estimated genome size. We find good collinearity with the rice genome and have captured most of the gene space. Streptochaeta is similar to other grasses in the structure of its fruit (a caryopsis or grain) but has peculiar flowers and inflorescences that are distinct from those in the outgroups and in other grasses. To provide tools for investigations of floral structure, we analyzed two large families of transcription factors, AP2-like and R2R3 MYBs, that are known to control floral and spikelet development in rice and maize among other grasses. Many of these are also regulated by small RNAs. Structure of the gene trees showed that the well documented whole genome duplication at the origin of the grasses (ρ) occurred before the divergence of the Anomochlooideae lineage from the lineage leading to the rest of the grasses (the spikelet clade) and thus that the common ancestor of all grasses probably had two copies of the developmental genes. However, Streptochaeta (and by inference other members of Anomochlooideae) has lost one copy of many genes. The peculiar floral morphology of Streptochaeta may thus have derived from an ancestral plant that was morphologically similar to the spikelet-bearing grasses. We further identify 114 loci producing microRNAs and 89 loci generating phased, secondary siRNAs, classes of small RNAs known to be influential in transcriptional and post-transcriptional regulation of several plant functions.

Gynostemium morphology and floral biology of Thottea duchartrei Sivar., A.Babu & Balach. (Aristolochiaceae), an endemic species from Western Ghats, India

Gynostemium is a putative floral structure formed by the fusion of the male and female reproductive parts (stamens and carpels) through a process during its development called synorganization. Most of the Indian species of Thottea Rottb. have a prominent gynostemium in their floral architecture, with varying degrees of adnation and complexity. Even though the gynostemium is a significant taxonomic marker for the inter-specific systematics in Thottea, the scepticism and arguments on deciphering its morphology and functional parameters, including the existence of staminodes, makes it imperative to be examined in detail. The present study is the first attempt in this line which aims to explore the morphological characters of gynostemium and reproductive biology of Thottea duchartrei Sivar., A.Babu and Balach., an endemic species in the Western Ghats. Stereo zoom microscopy, SEM and reproductive biological studies were conducted providing special emphasis to the gynostemium. Detailed analysis revealed the structural and functional diversity of gynostemium with regard to its components. The study also helped to recognize the columnar outgrowths on the gynostemium as staminodes. In total, the present study helps to solve the confusions regarding the functional identity of the gynostemium T. duchartrei with regard to its morphology.

Oat Floral Biology and Factors Affecting Seed Set

In India, oat is grown as fodder crop during Rabi season in north-western and central parts of the country and is now even extending to eastern region as well. The only commercially cultivated species in the genus Avena are Avena sativa, Avena nuda and Avena byzantine. Oat flowers are bit delicate when compared to other cereal floral structure and seed set is influenced by many factors during artificial hybridisation. This paper includes about floral biology of oat crop and also the various factors responsible for seed set during hybridisation viz effect of Interval Between Emasculation and Pollination, effect of temperature for seed set and any Injury to floral Parts during hybridisation.

The Streptochaeta genome and the evolution of the grasses

In this work, we sequenced and annotated the genome of Streptochaeta angustifolia, one of two genera in the grass subfamily Anomochlooideae, a lineage sister to all other grasses. The final assembly size is over 99% of the estimated genome size, capturing most of the gene space. Streptochaeta is similar to other grasses in the structure of its fruit (a caryopsis or grain) but has peculiar flowers and inflorescences that are distinct from those in the outgroups and in other grasses. To provide tools for investigations of floral structure, we analyzed two large families of transcription factors, AP2-like and R2R3 MYBs, that are known to control floral and spikelet development in rice and maize among other grasses. Many of these are also regulated by small RNAs. Structure of the gene trees showed that the well documented whole genome duplication at the origin of the grasses (ρ) occurred before the divergence of the Anomochlooideae lineage from the lineage leading to the rest of the grasses (the spikelet clade) and thus that the common ancestor of all grasses probably had two copies of the developmental genes. However, Streptochaeta (and by inference other members of Anomochlooideae) has lost one copy of many genes. The peculiar floral morphology of Streptochaeta may thus have derived from an ancestral plant that was morphologically similar to the spikelet-bearing grasses. We further identify 114 loci producing microRNAs and 89 loci generating phased, secondary siRNAs, classes of small RNAs known to be influential in transcriptional and post-transcriptional regulation of several plant functions.

A new Rorippa species (Brassicaceae), R. hengduanshanensis, from the Hengduan Mountains in China

A new species of genus Rorippa, R. hengduanshanensis, from the Hengduan Mountains, is described herein. Comparing the floral structure and overall fruit morphology of R. hengduanshanensis with similar taxa (e.g., R. benghalensis, R. dubia, and R. indica) revealed a series of morphological differences, both qualitative and quantitative. R. hengduanshanensis differs from R. benghalensis in the ebracteate racemes; from R. dubia in the flattened silique, the presence of four petals and the ploidy level (2n=6x=48); and from R. indica in the uniseriate seeds. Phylogenetic analyses using three plastid markers (psbC-trnS, trnG-trnM, and trnL) further revealed clear interspecific divergences that can distinguish R. hengduanshanensis from its morphologically related taxa.

Floral structure in Thismia (Thismiaceae: Dioscoreales): new insights from anatomy, vasculature and development

Thismia is characterized by an exceptionally complicated floral morphology that is currently not understood properly. In the taxonomic literature, descriptive rather than morphological terms are often applied to parts of the flower in Thismia, relating to the general appearance of the floral organs instead of their precise homologies. Precise understanding of the floral structure is complicated by the rarity of Thismia spp. and the paucity of appropriate material. Here we provide a comprehensive study of reproductive organs of three Thismia spp. (T. annamensis, T. javanica and T. mucronata) including the first investigation of inflorescence architecture and early floral development in Thismiaceae. We found a hitherto unknown diversity of the reproductive shoots in the genus, manifested in the number of floral prophylls (two or three, in contrast to a single prophyll in the vast majority of monocots) and in the branching plane resulting in two distinct inflorescence types, a drepanium and a bostryx. We report the non-acropetal sequence of initiation of floral whorls (with stamens being the last elements to initiate), never previously described in monocots, and the gynoecium composed of completely plicate carpels, also a rare feature for monocots. Floral vasculature is relatively uniform in Thismia, but significant interspecific differences are found in tepal innervation, including the number of tepal traces; some of these differences are not immediately related to the external tepal morphology. We argue that the annulus, which acts as a roof of the hypanthium, possesses an androecium nature and represents congenitally fused bases of stamen filaments. We describe the stamens as laminar structures, which are also shortly tubular in the distal part of the supraconnective with the adaxial tubular side forming a skirt-like appendage. Finally, the placentas, which are column-like when mature, are initially parietal, becoming secondarily similar to free-central placentas through schizogenous separation from the ovary wall.