Variations in Genome Size of Turnip Landraces from Two High-altitude Environments

Abstract

<jats:p><jats:italic>Brassica rapa</jats:italic> var. <jats:italic>rapa</jats:italic> (turnip) is considered a main source of food for the inhabitants of the Qinghai-Tibetan Plateau (QTP) and its adjacent highlands when other crops are scarce. The QTP ranges from lat. 25.59°N to 39.49°N and from long. 73.29°E to 104.40°E, whereas the Yunnan Plateau ranges from lat. 20.00°N to 29.16°N and from long. 96.00°E to 110.19°E. A comparison between the turnip landraces of two different plateau environments can provide a mechanistic insight into plant adaptation in highlands. The aim of this investigation was to understand the patterns in variation in genome size (GS) between the turnip landraces of two plateau environments. We used a well-established protocol to count chromosome number and performed propidium iodide flow cytometry to measure GS. No polyploidy was detected among the turnip landraces tested, and 15.5% variation in GS was observed between the landraces. No consistent pattern pertaining to GS variation emerged after the environmental variables were considered. Thus, we propose that such pattern may reflect the indirect effect of selection, random process, genetic drift, or some other factors on GS through interaction of life-form and phenotypic traits.</jats:p>

Genome Size Unaffected by Variation in Morphological Traits, Temperature, and Precipitation in Turnip

“…Usage of turnip as fodder is not conceptualized yet in the Himalayas, whereas China (Hengduanshan) enjoys a monopoly in turnip production. In our previous research, we have shown that GS of turnip landraces from the QTP were smaller than turnip landraces from the Yunnan Plateau [29]. In this research article, we show that the adaptation of turnip landraces to different environments is governed by nonassociated genotypic and phenotypic plasticity, this is supported by the experimental results of the following addressed questions;…”

“…A previous report [38] on GS investigation of the family Brassicaceae showed that the 1C genome size of Brassica rapa is 0.539 ± 0.018 pg, whereas the average 1C value of turnip reported in our report is 0.555 ± 0.000. The smallest GS of turnip landrace was reported in our study is from Qinghai province from altitudinal environment above 3600 m. Thus, we showed that turnip landraces adapted in the QTP are morphologically and genetically different compared to the landraces adapted in the Himalaya and the Hengduanshan region which we hypothesize due to the adaptation in the extreme climate [29]. This might be due to the fact that ultraviolet spectrum of the QTP is much stronger compared to the Himalayas and Hengduanshan resulting in a significant decrease in GS [39].…”

“…Morphological observation was carried out from the on-field data. The plant materials were photographed during the time of harvesting for their tuber dimension which was already documented in our previous study [29]. After transfer to the laboratory, seeds were stored at 15 • C and 15% relative humidity for 1 week to reduce moisture content to prevent mildew.…”

Genetic Diversity and Primary Core Collection Construction of Turnip (Brassica rapa L. ssp. rapifera Matzg) Landraces in Tibet Revealed via Morphological and SSR Markers

“…The genetic distances of 118 turnip landraces (0.121-0.932) featured much higher genetic diversity than the varieties found in Xinjiang "Qamugur" (the local name for turnip in Xinjiang, 0.098-0.160), turnips from different provinces of China (0.187-0.344), and varieties from Nordic areas (0.016-0.146) [1,47]. Moreover, a 15.5% variation in genome size has been observed between the landraces from two high-altitude regions [48]. This result may explain the much higher genetic diversity in Tibetan turnip landraces.…”

Pharmaceutical Potential of High-Altitude Plants for Fatigue-Related Disorders: A Review

“…An analysis [ 26 ] of days to flowering (DTF) on Brassica species (Qinghai–Tibet Plateau) showed that the external environment affected herbivore pressure, vegetative growth, and its genetic self-regulation. In addition, the genome size (GS) of turnip from plateau environments (Qinghai–Tibetan Plateau) was always smaller than that from lower latitudes (Yunnan Plateau), where 15.5% variation was observed [ 27 ]. Thus, turnip was conventionally named with regional characteristics for distinguishment (e.g., ‘Tibetan turnip’) and became a main source of food for inhabitants.…”